The present invention relates to a mold for and method of simultaneously pouring and more particularly to what is known as horizontal casting, i.e. casting of a multitude of castings in adjacent molds from a common, horizontal runner feeder.
In the past, the normal means of pouring a plurality of molds simultaneously has been through vertical or stack casting techniques. In this technique, the molds are placed one on top of the other and are positioned so that the runner feeder which connects the cavities of each mold is vertical. Molten metal, which is poured into the vertical mold's down sprue, falls to the bottom of the runner feeder to a point adjacent the cavity of the bottom mold. The molten metal experiences turbulence when it strikes the bottom of runner feeder after being poured. The bottommost mold is filled initially with the turbulent molten metal which in turn creates a casting of unacceptable quality. As the molds are filled from the bottom up, so is the runner feeder, hence new molten metal is continuously free falling from the down sprue to the top of the molten metal in the runner feeder. Turbulent molten metal is therefore flowing into each successively higher mold cavity, resulting in casts of poor quality.
Furthermore, when the molds are stacked vertically the static pressure of the molten metal causes what is commonly known as "burn out". Burn out occurs when the molten metal penetrates the mold material and causes ruptures or seepage at the mold joints. A burnout on a vertical mold can result in complete failure of all the castings which make up the vertical mold.
In order to eliminate the effects of turbulent molten metal on the quality of the cast article, the technique of horizontal casting has been developed. The technique is so named because the molds are placed in an abutting side-by-side relationship with a common, horizontally aligned runner feeder between the molds. Each mold has at least one cavity and ingate associated therewith. Molten metal flowing through the horizontal runner feeder flows into the mold cavities through their associated ingates. This method eliminates the high magnitude of turbulence associated with vertical runner feeders, but creates turbulence when the molten metal flows from the runner feeder into the mold cavity.
In addition, horizontal casting techniques and molds of the past have been subject to burn out problems and poor casting quality because of their design. Specifically, the molds have been of the investment and air-set type which are expensive and labor intensive because of the difficulty of fashioning a runner feeder integral with the mold and because the molds have been placed in abutting, side-by-side relationship. Furthermore, the ingates and the runner feeder have been sized so that molten metal is filling two adjacent molds simultaneously. Hence when burn out occurs there are at least two molds destroyed and the normal practice of destroying the rest of the molds.
According to the present invention, a horizontal mold arrangement for use in the casting of molten metal comprises a plurality of shell molds secured together in spaced, side-by-side relationship. Each mold has at least one mold impression or mold cavity formed therein below the runner feeder center line and ingate means connecting the mold cavity (ies) to a portion of the runner feeder. The runner feeder forms a weir associated with each mold and together with the mold forms a riser which lies above the mold cavity. The minimum cross-sectional area of the runner feeder is being less than the total cross-sectional area(s) of all ingates associated with a single mold. This last feature ensures that during the casting operation any turbulence created within the mold cavity is not trapped within the mold cavity as with the molds of the prior art. Hence, molten metal poured into the down sprue is channeled within the runner feeder to the first riser whereupon the molten metal begins to fill the mold cavity. Any turbulence eventually rises out of the cavity through the ingate and out into the riser area and is swept downstream by the molten metal in the runner feeder until it is eventually removed from the mold system. Therefore, the present invention solves several of the problems associated with the horizontal casting techniques of the past. Specifically, a burn out will only result in the destruction of one mold since all of the rest can be saved. In addition, molten metal turbulence has been minimized and therefore casting quality improved.
Accordingly, it is an object of the present invention to provide a horizontal casting technique which reduces the destructive effects of a burn out.
It is another object of the present invention to provide a horizontal casting technique which utilizes shell molds.
It is another object of the present invention to provide a horizontal mold system which reduces the turbulence of the molten metal to a minimum.
It is a further object of the present invention to reduce the total amount of liquid metal required to effectively feed appropriately designed riser feeders, thus saving remelting energy.
It is a further object of the present invention to provide an easily manufactured runner feeder for use with the horizontal casting technique.